This invention relates to a transparent protective laser shield and a method for making the same which is adapted to be interposed between a laser and a viewer for protecting the viewer from damage by laser beam radiation, and more particularly to such a protective shield in which chromophore dyes in the form of metallo-porphyrin complexes are diffused into the surface of a transparent host material, such as a plastic material, forming a diffused layer thereon thereby providing the host material with the absorption characteristics desired.
In a host of medical, industrial and other applications a laser beam may be employed for cutting, fusing or performing other functions which may cause contact with the eye either by direct viewing or reflection from the object being worked on. Since the eye collects and focuses the energy, and since the laser beam is generally concentrated, considerable damage can result from the application of this energy to the optic nerve. The same is true when the viewer happens to be a light sensitive detector which may be monitoring the particular operation being performed by the laser. Accordingly, laser shields have been provided to enable viewing the laser beam in its environment without being subjected to the danger of concentrated beam energy. For example, U.S. Pat. No. 3,853,783 describes the use of vanadyl phthalocyanine sulfonamides in plastic compositions to protect the eyes from exposure to laser radiation with wave lengths in the region of about 620 to 720 nanometers. The problem is to get the dyes, namely the vanadyl phthalocyanines to be readily soluble in the various transparent plastics which are used for the shields. In this patent the dyes are directly mixed with the plastic material and molded or cast into plates or goggles or shields, etc. which requires difficult and time consuming procedures and extreme difficulty in being able to thoroughly mix or dissolve the dyes in the plastic material.